Category: transition metal
Atomic number: 30
Colour: blueish white
Melting point: 420°C (788°F)
Boiling point: 907°C (1,665°F)
First identified: 1746
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Category: transition metal Atomic number: 30 Colour: blueish white Melting point: 420°C (788°F) Boiling point: 907°C (1,665°F) First identified: 1746 |
Pinning down when an element was ‘discovered’ can be tricky – sometimes it is best to count the date when it was first refined by a chemist, while for other elements the appropriate date may be when it was first found or identified. We know that the Romans used zinc, and there is archaeological evidence that it was being refined in India from the twelfth century until the sixteenth century. Historians generally record the German chemist Andreas Marggraf as being the first to recognize it as a new element in 1746, but the Flemish metallurgist P. Moras de Respour had written about the extraction of the metal from zinc oxide in the previous century.
The most common use of zinc is for galvanizing steel to prevent corrosion – this process was invented by Luigi Galvani (who is also remembered for having used an electric current to make frogs’ legs twitch). The usual method is hot-dip galvanization, in which iron or steel is briefly submerged in liquid zinc: this creates a thin layer, which protects the metal beneath.
When Baron Haussmann renovated the city of Paris in the nineteenth century, for the rooftops he mainly used an alloy that was 80 per cent zinc. The beautiful silvery-grey roofs have become a signature image of the city, inspiring many artists and film-makers. They have recently been recognized as a ‘priceless cultural asset’ and are likely to be given Unesco World Heritage status. They have the advantage of being environmentally friendly – rainwater that runs off zinc does not leach up any of the metal (unlike lead and other heavy metals used for the same purpose).
Zinc can also be alloyed with copper to produce brass, which is widely used for everything from doorknobs to zips and, of course, the brass instruments in an orchestra. Its compounds include zinc sulphide, which is used for making paint and fluorescent lights, and zinc oxide, used in a wide variety of products, most notably as the main ingredient of calamine lotion.